1. Field of the Invention
This invention relates to an apparatus and method which is designed to characterize the electro-thermo-mechanically-coupled mechanical and physical properties (e.g., the viscoelastic and fatigue properties) of materials, including ferroelectric materials as well as composite materials containing ferroelectric inclusions and having electromagnetically-tunable mechanical performance.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References”. Each of these publications is incorporated by reference herein.)
In the quest for novel materials with extreme and tunable physical properties, active composite materials containing phase-transforming inclusions have been developed in recent years whose overall viscoelastic performance and properties (such as the dynamic stiffness and damping capacity) can be tuned by thermally controlling the phase transition[1]. In particular, experiments on Sn—BaTiO3 composites [1,2] have confirmed extreme increases in dynamic stiffness and damping by orders of magnitude due to a thermally-activated transformation of the BaTiO3 phase. However, it has also become evident that the need for a highly sensitive temperature control makes those materials unattractive for most practical applications. In contrast, materials with electromagnetically-controllable mechanical properties (e.g., materials that change their stiffness and damping by the push of a button) could serve numerous scientific and technological applications. Understanding and ultimately technologically exploiting such electro-thermo-mechanically-coupled time-dependent properties of materials (e.g., of ferroelectric materials or of composites containing ferroelectric phases) requires currently-unavailable measurement capabilities. Existing techniques of Broadband Viscoelastic Spectroscopy (BVS) [3] or Dynamic Mechanical Analysis (DMA) are insufficient because they cannot independently apply electromagnetic and mechanical loads under careful temperature control over wide ranges of frequency. A new apparatus and method that provide qualitative and quantitative data to characterize the electro-thermo-mechanically-coupled properties of materials enables the discovery of new active composites with extreme properties, of new ways to actuate existing materials, and of new physical phenomena.